X-ray apparatus



Jan. 16, 1951 Filed Sept. 29, 1945 D. SUSSIN ETAL X-RAY APPARATUS 2 Sheets-Sheet 1 IN VEN TORS @EMWM M ma/5 M Jan. 16, 1951 D. SUSSIN ETAL X-RAY APPARATUS 2 Sheets-Sheet 2 Filed Sept. 29, 1945 WEE INVENTORS WWOM ATTORNEYS Patented Jan. 16,1951

X-RAY APPARATUS David Sussin, South Fort Mitchell, Ky., and William C. Kuhlman, Cincinnati, Ohio, assignors to Manufacturing Company,

Covington, Ky., a corporation of Ohio Application September 29, 1945, Serial No. 619,334

The Kelley-Koett 14: Claims. 1

This invention relates to X-ray systems and more particularly to a control system for X-ray apparatus.

It is the principal object of the invention to provide a control system for X-ray apparatus which is simple and rapid in its adjustment, which prevents the occurrence of conditions which would be dangerous to the equipment or to personnel, and in which suitable indication is provided to apprise the operator of the condition of the equipment at all times.

It is a further object to provide such a control system in which the settingo-f the ln'l-ovoltage to be applied to the X-ray tube is continuously adjustable without steps and is accomplished from a control panel by power operation under simple push button control by the operator.

It is also an object to provide a variable ratio transformer for preselecting the kilovoltage to be applied to the tube and additional controls for the selection of the desired values of filament voltage and resulting tube current and to provide proper indication of the actual kilovoltage for each selected current value.

It is a further object to provide a control panel behind which the operating equipment is located and containing only simple control members for effecting the controls as above described, the panel having suitable indicators to enable the operator properly and intelligently to control the Fig. 1 is a front elevational view of the face or control panel forming the front wall of a casing receiving the control mechanism;

Fig. 2 is a perspective View looking toward the rear of the casing;

Fig. 3 is a diagrammatic view showing the various circuits and controls provided in and forming part of the system;

Fig. 4 is a diagrammatic view showing a suitable form of control motor; and

Fig. 5 is a schematic view showing an interlocking mechanism for the push button switches which select the tube current.

In the provision of an X-ray control system it is important to provide for the proper operation of the tube under desired conditions of kilovoltage and tube current, while at the same time affording adequate protection against the possibility of operating the tube in the absence of proper operating conditions. For example the voltage to be applied should be variable over a rather wide range, as desired for different techniques, and similarly it should .be possible to adjust or select predetermined filament voltages and the corresponding values of tube current or ma. values over a substantial range within the permissible rating of the tube. In order properly to protect the equipment, as well as avoiding possible injury to personnel, it is important to prevent the possibility of operating the tube at is maximum current and maximum voltage, there being a range of maximum safe voltage conditions for the range of tube currents, in order to be Within safe operating limits.

In accordance with the present invention suitable controls are provided for preventing the operation of the tube when a kilovoltage setting has been selected which is in excess of the predetermined safe condition for the selected value of tube current. However the system not only prevents the occurrence of such improper operating condition :by making it impossible to energize the tube when such wrong technique has been used, but it also afiords a direct visual indication to the operator in advance of the actual energizing of the tube circuit, so that he will be advised promptly that the wrong technique has been attempted, even before he actually tries to operate the tube.

Further, the apparatus is arranged with its working mechanism located in an enclosed and concealed position behind a control panel with only the simplified controls appearing on the face of the panel which are necessary for actual operation. The continuously variable autotransformer is power operated and a push button control is accessible to the operator on the face of the panel, requiring merely the pressing of one or another of two push buttons to cause increase or decrease in the kilovoltage setting.

Likewise a series of controls are provided on the panel for selecting the different values of ma. or tube current, and in addition line voltage compensating controls are provided with an indicator having a normal position so that by adjusting the line compensating transformer to bring the indicator to its normal position, the operator knows that the system is energized at a proper voltage condition and that thereafter the voltages and currents produced will be in accord with the indicated values.

In conjunction with the power operation of the autotransformer, it is important to provide for indicating to the operator the setting of the transformer at all times, thereby enabling him properly to control the adjusting motor to secure the selected value desired. However the actual kilovoltage applied to the tube will vary in accordance with the values of tube current, a given setting of the transformer for one current resulting in a lower actual voltage effective upon the tube if the tube current is increased. In accordance with the invention therefore, a plurality of scales or indicating means are provided and are suitably correlated with the selection of the tube current values so that only the selected scale corresponding to the selected value of tube current, is readable, thus affording an accurate and direct reading of the applied kilovoltage.

In addition, suitable interlocking controls are provided for preventing operation of the tube when there is a failure in the flow of the fluid cooling medium, or when it reaches =an excessive temperature. This interlocking mechanism functions to prevent energization of the tube when the conditions are abnormal; in addition, the operator is advised by suitable indications visible upon the face of the control panel so that he will know the particular condition which is abnormal, and can thus take suitable steps to correct it.

Referring to the drawings which illustrate a preferred embodiment of the invention, the control panel is indicated generally at Ill, being mounted upon a frame or housing structure l2 which is closed upon three sides, leaving the back open for accessibility, a suitable cover panel being provided as desired to thus enclose the entire control mechanism. Such control mechanism received within the housing is thus located behind the control panel It], only the necessary control elements and indicating devices appearing upon the face of the panel so that the control of the system is rendered simple, rapid, and reliable. The relays and other electrical equipment are preferably mounted on the side of housing l2, their position being indicated generally by reference numeral [4, the use of a, cover as shown being optional.

The main power supply is indicated at 20, where it is represented as a three wire source, the neutral wire being grounded. The two main power lines are fused as shown at 2| and are controlled by main line contactor 24 having an operating coil 25. Energization of this contactor is under the control initially of a key switch 21 which is mounted upon the face of the panel and which requires the insertion and turning of a key in order to be unlocked and thus provide for .energization of the entire system.

When the key switch 21 is closed, an energizing circuit is established through the back contact 30 of relay 3|, thus closing the energizing circuit to contactor providing relay 3| remains deenergized. -The circuit for relay 3| includes a, current coil 33 in the main line circuit which upon the existence of an overload will close its contact 34 which thus energizes relay 3|, causing it to break its contact and close its upper contact '35. The opening of contact 30 deenergizes the main line switch 24, and the closing of contact 35 establishes a holding circuit for the relay, at the same time energizing a signal light 36 mou ttransformation ratio.

ed on the face of the control panel which is connected in parallel with the relay so that notwithstanding the subsequent disappearance of the overload, the relay 3| and indicator 36 will remain energized until the key switch 21 has been switched to off position and then returned to on position. The operator is thus notified that an overload has occurred and with the key switch turned to off position can take suitable action with respect to clearing the cause of the overload before again attempting to energize the circuit.

One side 38 of the main line circuit extends to the zero point 40 of the variable ratio transformer or autotransformer 42. The other main line circuit 43 extends through a line compensating transformer 44 having connection with a regulating transformer 45 through the continuously variable contact 46, adjustable at all times by external handle 46' so that the voltage may be regulated while the tube is energized. Such connection is highly desirable in the present circuit since it permits of securing a continuously variable voltage without the use of resistors and the like which frequently have open circuit positions, causing the breaking of the main line circuit and thus giving rise to objectionable surge and transient voltage conditions. Further the transformer 45 need not carry the full line current, but may have a limited capacity such as to provide for adding or subtracting only a portion of the main line voltage to compensate for the ordinary range of line variations.

Connection is made by adjustable contact 41 to a selected one of the taps 48 of the transformer 42, to thus establish the major adjustment in the transformer, and making the system applicable to systems having a nominal voltage range for example of from about 210 volts to 250 volts. This major adjustment is made usually at the time of installation, and ordinarily does not require change thereafter, the line compensating transformer 45 being sufficient to provide for all ordinary line voltage variations.

In order that the operator may know at all times of the actual peak voltage condition eifective upon the transformer 42, a voltmeter 50 is mounted on the panel and is connected to the zero terminal 40 of the transformer and through a suitable resistor 5| to a fixed one of the taps 48. It will thus be clear that this meter responds to and gives a proper indication of the voltage condition applied to the transformer. It is not necessary that this meter be fully calibrated, and for purposes of simplicity it is preferred to have only an index mark so that the operator may adjust the compensating transformer 45 as necessary to bring the needle on the meter opposite the indicating mark. In that position proper uniform voltage is applied to the transformer 42 so that it will have a uniform and known value of volts per turn.

In order to provide a source of lower voltage for control purposes, an intermediate tap 55 is brought out from the transformer 42 at a position which will give approximately volts between such tap and the zero point 40. The various connections to this control circuit will be described more in detail hereinafter.

In order to provide for power actuation of the transformer under control of the operator, the vertically extending shaft 51 is mounted on adjustable arm 55 which is movable to vary the A gear train 58 is connected to shaft 51, coupling the same with the shaft of a reversible motor 60. The motor is mounted in a convenient position in the rear of the panel, and comprises'a field winding BI which is connected for continuous energization to terminals 40 and 55. It also has a double armature winding 62, 63, the center point of the two windings being connected to ground. When the other terminal of either one of these windings is grounded, a closed circuit is provided which in conjunction with the continuously energized winding 6 I, provides for selective control of the operation of the motor in opposite directions.

Such control is provided for the operator in the form of a pair of push buttons '65, 66 which are mounted for convenient operation on the face of the panel, and marked for example Raised voltage and Lower voltage, respectively. A ground is provided between the push buttons as shown at 61, and upper and lower limit switches 68 and 60 arranged to be engaged by the adjustable arm 56 as it reaches the respective limits of its travel are provided for interrupting the circuit of the armature winding which is energized to prevent damaging of the mechanism.

In operation, it is only necessary for the operator to press one or the other of push buttons 65 or 6%, thereby closing the circuit through motor winding 02 or 63, which results in the operation of the motor in a selected direction, to raise or lower the voltage setting of the transformer, as long as the push button is held.

A connection is made from the adjustable autotransformer control arm 56 through fuse I to one side of the step up or high tension transformer II located in the tube head. The tube head is indicated diagrammatically by the dotted outline I2, and may be remotely located with respect to the control panel and connected thereto through a control cable. The primary circuit of transformer ll is completed through connection I3 and the X-ray contactor indicated generally at I5. This contactor comprises an operating coil and an upper contact element 16 which upon energization of the coil closes first through a surge resistor ll, followed shortly thereafter by the closing of the main contact 18 to connect the autotransformer directly with the primary of the transformer II.

The tube itself is shown at 80 with its elements connected to the secondary SI of the high tension transformer. The filament circuit is supplied from the secondary 82 of a filament transformer having a primary winding 83, such transformer equipment being located in the tube head 12 and suitably insulated for the high voltage to which it is subjected. Connection is made between the control equipment and the tube head by a multiple cable indicated at 85.

In order to provide for proper selection of the desired values of tube current, usually referred to as the ma. values of the tube, suitable means is provided accessible to the operator by means of which he may pro-select the value of tube current desired. This accomplished through the variation of the filament voltage on the tube, a plurality of push buttons being mounted on the control panel in accordance with the present invention. These buttons may be selectively actuated and are suitably interlocked by any desired form of push button mechanism such as that indicated in Fig. comprising a latch bar 80 having tongues 81 which may be latched respectively in the shafts of the various push buttons indicated diagrammatically at 94 to 91.

Connection is made to the terminals of the control circuit 40, 55 on the protected side of fuse 88, a suitable indicating device 89 being con nected across this circuit to indicate to the Operator that the main line is on or energized. Connection is made through a stabilizer $0 which may be suitably constructed in accordance with U. S. Patent No. 1,967,108, assigned to the same assignee as this application, such stabilizer providing for maintaining a substantially uniform voltage condition under varying load on its output side 9|, 92. As shown line 9I is connected directly to one side of the primary of filament transformer 83.

Four push buttons are shown which correspond to the range of ma. settings desired such for example as 5, 10, 15 and 30 ma., respectively. A corresponding number of individually adjustable inductive regulators I00, IOI, I02 and I03 are connected in series relation in line 92 of the stabilizer output circuit and short circuiting connections are made for each of the regulators I00 through I02 which are closed by a lower set of contacts I05, I00, and I0! which are carried respectively by the push buttons 95, 96 and 91. The use of inductive regulators for preselecting the values of filament voltage is desirable because of their ability to maintain substantially uniform operating characteristics notwithstanding changes in temperature under load.

In operation the system is arranged to function as follows. When the lowest range push button 94 is operated, there is no short circuiting circuit, and all of the four regulators are arranged in series circuit, thereby providing a minimum value of voltage which is applicable to the primary 83 of the filament transformer. When push button 535 is depressed for the next higher value of ma., its lower contact I05 short circuits regulator I00, thereby providing for establishment of a higher voltage on the filament transformer. Similarly operation of push button 96 short circuits regulators I00 and I0 I, while operation of push button 91 short circuits all except regulator I03, thereby providing maximum filament voltage.

, An increase in the kv. applied to the tube will normally tend to cause an increase in the tube current, and in order to provide for securing predetermined values of tube current notwithstanding changes in the kv. setting as determined by the adjustment of the autotransformer 42, a filament compensating transformer I I0 is provided in the energizingcircuit to the primary winding 83 of the filament transformer. As shown the winding II I of this transformer is connected directly across the power output of the autotransformer 42, and the voltage effective thereupon will thus vary in direct relation with the setting of the adjustable transformer arm 50. This winding is connected so that the voltage of winding H0 will be in opposition to the main voltage in the filament circuit and thus as the voltage on the autotransformer is increased, a greater ops posing voltage is applied in the filament circuit, reducing the filament current by the proper amount to maintain substantially uniform tube current. Fine adjustment of the compensating efiect may be further accomplished through the setting of a vernier rheostat I I2 connected in the line. A suitable fuse element H3 is also preferably included for the protection of the circuit.

It is also found that the current flow in the tube has an effect with respect to the applied kilovoltage, the kilovoltage as actually measured. at the tube for any fixed setting of the autotransformer control arm being reduced with increase in the tube current. In order to enable the operator to obtain desired values of kilovoltage at difierent ma. values and thus to establish and follow a definite technique, it desirable to provide for application of the proper kilovoltage to the tube, notwithstanding a change in the ma. setting of the tube current. It is found that the true applied kilovoltages may be approximated with a sufiicient degree of accuracy without the use of a separate scale for each of the ma. settings, and in practice with the four values of ma. setting referred to above, it has been found that two scales may be provided for properly indicating the kv. values.

The two scales are shown at I I and I l6, beingcarried directly upon the adjustable shaft 57. of the variable transformer 42, so that they will turn in directly coordinated relation with the setting of the autotransiormer arm 56. Preferably the shaft is extended upwardly and the two scales are mounted at its upper end in position where they extend toward an opening I I I on the face of the panel through which they can be viewed by the operator. It will be understood that the two scales are calibrated differently in accordance with the actual kilovcltages effective upon the tube, corresponding to the different transformer settings at different selected values of tube current.

In order to provide for selective reading of the proper scale, that is, the scale which contains the correct reading of kilovoltage corresponding to the selected value of tube current, a pair of illuminating means IIB and H9 are provided which are associated respectively with the scales H5 and HG so that when either light is energized, only the scale corresponding thereto will be visible and readable by the operator. Selective energ-ization of the lights is accomplished by means of circuits controlled by upper contacts 52c, I2I, I22 and I23 on the several push button switches 94 through 91. In the circuit as shown, contacts I20 are in the circuit of light I89, so that upon depression of push button 524 a circuit is complet ed to terminal 48. The opposite side of the circuit is connected directly to terminal 55 and thus light IIS and the corresponding scale H6 will be illuminated.

Depression of any one of the push buttons 95 through 91 will close its corresponding contacts I2I, I22, or IE3 to complete a circuit for light II8 between points 49 and 55, thereby selectively illuminating the scale H5. In this case it has been found that a better approximation of the correct kv. readings can be effected by illuminating the scale III} only in case the push button corresponding to the lowest ma. setting is pressed, scale H5 providing proper kilovoltage indication for all of the three remaining push button switches 95 to 97!. It will be evident however that the illumination of the desired scale may be selectively controlled as desired for operation of any of the push buttons, and that a greater number of scales may be used and may be selectively illuminated as desired.

It is important for the protection of the X-ray tube that it be operated only when properly cooled by a flow of cooling fluid such as oil which itself does not attain an excessive temperature. Oil is desired because it must circulate in the high tension zone of the tube and must have proper dielectric strength to withstand the voltage condition to which it is subjected. The oil is circulated by a pump I25 operated by motor I21 connected to terminals 40 and'55 through fuse I28. In turn the heat is withdrawn from the circulating oil by a flow of cooling water, and it is also important to prevent operation of the system except when there is a proper flow of this coolingwater. To provide such control, a water pressure cutout switch I 30 is arranged to be normally open but to be closed upon the existence of the proper pressure of cooling Water as supplied through conduit I 3!. When closed, switch I30 establishes a circuit for a suitable indicating device I32 connected across terminals 40 and 55 which is mounted upon the control panel and suitably marked such as Water pressure on to advise the operator accordingly. An oil temperature cutout I33 is provided in proper heat responsive relation to the oil body, and arranged to be opened by a suitable thermostat when the oil temperature exceeds predetermined safe value. As long as switch IE3 is closed, it completes a circuit for an indicator 34 also connected across terminals All and 55 and which is mounted upon the control panel and suitably marked such as Oil temperature correct, for the information of the operator.

An oil pressure cutout switch I35 is arranged to be normall open but to be closed in response to development of the proper oil pressure in the circulating system, a applied through conduit I38. Upon closing, the cutout switch I35 establishes a circuit for the relay coil I31 which in turn has lower switch arm I38 that closes to provide for energizing the indicator I39, also mounted upon the control panel and suitably marked such as Oil pressure correct. As will be evident from the diagram, indicator I39 is also energized from the control circuit 40, 55. Relay I3! also has an upper switch arm I40 which upon closing Will connect to terminal MI. Thus when the several cooling conditions are proper terminal I4I will be energized by connection with terminal 40, and terminal I42 will be energized by connection with terminal 55.

A timer is provided for controlling the time during which an exposure is allowed to continue, after the tube has been placed in operation. However it is usually desired to allow the tube to warm up for a period of time before the actual exposure is made, such period sometimes running into several minutes. If the timer had been inadvertently left in on pcsit-ion, providing for the opening of the shutters and the resulting transmission of X-ray toward the object, it is evident that serious injury could result to personnel during this period. For this purpose it is desired to interlock the timer with the tube operation in such a way as to require that when the tube is first energized after a period of non-use the timer be placed in off position, resulting in the closing of the shutters, before the tube can be energized.

For this purpose the timer shown generally at I45 is provided with a switch arm I46 accessible upon the face of the panel and movable from an Oil contact I4! to an On contact I48. Switch arm I46 i connected directly to terminal 40. Provided switch I 46 is on contact l i'l, i. e., the on position, a circuit is established to relay coil I55, the opposite side of which is connected directly to terminal 55. Relay I 59 upon closing establishes a circuit through its lower contact I52 which by-passes switch arm I46 and contact I41, thereby providing a hold-in circuit directly connected to contact Mb Relay I50 will therefore remain energized after the timer switch has been moved from its Oif to its On position. This however will require a definite act on the part of the operator and will prevent the possibility of the circuit being energized with the timer inadvertently in On position.

Relay I50 also has an upper contact I54 which upon closin connects from terminal I42 to one side of the X-ray on or start button I60. This is a control button located on the face of the control panel in position to be actuated by the operator, for controlling the energization of the X-ray contactor to close the main energizing circuit to the high tension transformer, as above described.

The circuit for energizing the operating coil of contactor 15 is provided with an interlocking control of such character as to assure against the circuit being closed under a condition where an excessive kv. settin has been selected for a given ma. selection. That is, the tube may be operated at its maximum kv., or at its maximum ma. setting continuously, but the controls should not be set to produce both maximum kv. and ma. for any one operation as this will be damaging to the tube. Suitable interlocking connections are therefore provided to prevent operation of the tube whenever the kv. setting for a selected value of tube current is in excess of the safe operatin range. This is accomplished through the provision of a relay I65 one side of the operating coil of which is connected to the supply line M from the stabilizer, through connection I61. The opposite side of the operating coil is connected from the opposite side 92 of the stabilizer output through line I68 to the series of normally closed or back contacts I05, I06, I 01 of the push button 95, 96, 91 respectively, and thence to line I69.

From the above it will be seen that when the push button 94 is operated, corresponding to the lowest ma, value, a positive circuit is completed for the energizing of relay I65, thus making possible the energization of the X-ray contactor 15 for the entire range of kv. settings. Upon the energizing of relay I65, it closes its upper contact I15 and a circuit is then completed from terminal I M through the closed contact arm I15, through the X-ray ofi or Stop push button I18, to one side of the operating coil of the X-ray contactor I15. The circuit to the opposite side of this operating coil has previously been traced from terminal I42 through. the closed switch contact I54 of relay I50, so that upon the closin of the start push button I60, the energizing circuit for the contactor 15 is completed and the same closes. Upon closing it establishes a lock-in circuit through its switch contact I80, by-passing the start button I60 and retaining the contactor in operative position until the circuit is broken at stop button I18. As previously described, switch arm 16 closes slightly in advance of switch arm 18 and the tendency to cause objectionable surges is thus overcome.

When however one of the remaining ma. selector switches for a higher ma. value has been operated, such as switch 95, it will be seen that the circuit for the operation of relay I65 is broken at switch contacts I05, which are now in the lower position opening the circuit through connection I58 and thus deenergizing relay I65. Since this relay must be energized in order to close the circuit to the X-ray contactor 15, it is evident that under these circumstances operation of On push button I69 will be ineffective to energize thetube.--

To enable the system to be operated within a safe range of kv. settings which will not overload the tube at the selected ma. value, a parallel circuit is provided around switch contacts I05 including cam operated switch I which is arranged to be operated by a cam Hit movable with and secured to the shaft 5? of the transformer 52. Cam I86 is of predetermined angular extent and at all settings of the control arm 56 up to the critical range for the selected ma. value, the cam I85 remains out of contact with switch I85. In this range the switch I85 thus remains closed and completes a by-pass circuit around the switch contacts I05 so that the circuit is completed and the relay I65 will remain energized, permitting operation of the X-ray contactor it under the control of push buttons I60 and I18, as previously described. When however the control arm 58 is operated to a range above the safe range for the selected value of ma., cam I85 engages cam switch I85, opening the circuit, thus deenergizing relay I55, and preventing the closing of the X-ray contactor.

In order to provide proper indication so that the operator will know in advance that he has selected a value of kv. in excess of that proper for the selected ma. value, means is provided for indicating this condition on the face of the control panel. This is accomplished by the provision of back contacts I90 on relay I65 which upon deenergization of the relay complete a circuit for indicator I9I, connecting the same directly across terminals ii and 55. The indicator I9! suitably carries a designation such as Wrong Technique, and it will be apparent that the circuit for this indicator is completed in advance of any attempt to operate the 'X-ray tube, thus immediately making known to the operator that he has made a selection of values which are improper or unsafe. Being -warned of that fact, he can make suitable correction at once, even before attempting to close the tube circuit which of course is prevented while this condition exists.

Similar circuits are provided for by-passing switch contacts I06 and I01 of the ma. selector switches and 91. As shown this includes the cam operated switches I94 and I95 actuated by cams I96 and I91 respectively, the successive cams I88, I96 and I91 having a progressively greater arcuate extent so that they engage their respective switch operating member at a progressively lower setting of the control arm of the autotransformer, to increasingly restrict the safe kv. setting with increase in the selected ma. settings.

Connected in parallel with the operating coil of X-ray contactor 15 is relay 2&8 which closes concurrently with the closing of the contactor, establishing a circuit from a high voltage point on the autotransformer through line 2iI to an ma. indicator 202, represented as a glow type of lamp. The opposite side of the lamp is connected to the zero point 45 of the autotransformer. The glow lamp which is visible from the face of the panel will thus provide an indication to the operator that the magnetic switch 15 is closed. Further, an hour counter 205 is connected in parallel with the operating coil of contactor 15 to provide for integrating the total time the X-ray tube is in operation.

When it is desired to make an exposure, the timer switch I 36 is manually moved to its left hand or On contact I58, thereby completing a circuit from terminal 40 through the timer switch" 76 to the energizing coil of relay 2I0, the circuit being completed to the opposite terminal 55. Upon being energized, relay 2H} closes its upper contact 2l2 which closes a supply circuit from the closed switch arm I15 of relay I65 (the switch arm I15 being connected to the live terminal Mi as previously described) thereby supplying power to the timer motor 214', the opposite side of which is connected through line M5 to switch arm I80 of contactor l5, and thence through the closed switch arm Ha l of relay E58 to terminal I42. The timer thus runs for the predetermined length of time for which it has been set by the operator. At this time the timer mechanically moves its switch arm ME from the On contact M8 to Off contact I41.

Relay 2!!! upon being energized also raises its lower switch arm 2m to shift the ground connection thereof from the lower switch point to its upper switch point. Connections are made from these two switch points respectively through leads 2H, 2l8 to a reversible shutter operating motor indicated generally at 220 within the tube head. This motor is similar to motor til and comprises one winding which is continuously energized from terminals 40 and 55, and a pair of windings connected with the center point thereof grounded. Thus upon completion of a ground circuit through either one of the pair of windings, the motor will be operated in a selected direction to cause either the opening or closing of the shutter under the control of switch arm 2| 6. It will further be observed that when relay 2"! is deenergized the switch arm 2l6 maintains contact with its lower contact point, thus maintaining the shutters in normally closed position. 0nly in response to energization of the relay Eli! is the switch arm 216 raised to energize the circuit for opening the shutters. The shutters thus open upon the movement of switch arm MS to the On position and the time motor also begins to run. When it has been on for the preselected time, it moves the switch arm to Oif position, deenergizing relay 2H], causing the closing of the shutters, and also opening its own energizing circuit.

Interlocking switch arms 225 and 226 provide for actuating switch assemblies 221 and 228 respectively, to provide visual indication of the shutter condition so that the operator will be properly advised at all times. Connection is made through line 55 and. the upper set of switch contacts 228 so that upon opening of the shutters a signal light 230 is energized, by connection thereof to terminal 40. Similarly when the shutter opens, a circuit is completed through the upper pair of switch arms 22! to indicator 232, also mounted upon the control panel and visible to the operator. The indicators may be suitably marked such as Closed shutter and Open shutter, respectively.

It may also be desired to incorporate an ma. meter shown at 235 one side of which is connected to ground and the other side being connected through a suitable high resistance 236 to the mid-point of the high tension transformer. This provides a direct measure of the tube current and is also suitably mounted upon the face of the panel for direct reading by the operator.

The invention thus provides a control system for X-ray apparatus which properly and reliably protects the equipment as well as personnel against the establishment of improper or dangerous conditions, and in addition afiords visual indication to the operator in advance of any of the critical conditions which may be abnormal and which would function to prevent operation of the system. The operator is not left however without information as to which condition is abnormal, but by reference to the control panel he is fully informed and may take suitable steps to correct such abnormal condition. Further the entire operation is rendered simple and direct, eliminating the need for manual adjustment of the variable ratio transformer, and providing simple push button control thereof. Furthermore correct settings of both kv. and selected ma. are obtainable throughout the range of tube operations, thus enabling the system to be operated with definiteness and certainty, contributing to safety as well as uniformity of results.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An X-ray control system adapted to be energized from a power line forming a high voltage supply for an X-ray tube and capable of being adjusted while said tube is energized without causing damage to said tube which comprises a variable voltage line compensating transformer for regulating the voltage of the power line to a predetermined substantially uniform value, and a separate variable ratio transformer supplied by said compensating transformer, said variable ratio transformer having a single continuous series of taps thereon, and a single adjustable member for engaging said taps in sequence and maintaining a continuously closed circuit thereto throughout its entire range of movement providing for adjustment of the voltage supplied to said tube substantially free of surge conditions.

2. The system as defined in claim 1 in which the line compensating transformer selectively increases or decreases the line voltage supplied to said variable ratio transformer through a coupled circuit and without carrying the full line current thereof.

3. An X-ray control system comprising a variable ratio transformer for supplying a variable voltage to the circuit of the X-ray tube, said transformer having a single adjustable member final kilovoltage applied to the X-ray tube corresponding to the selected tube current.

4. An X-ray control system comprising a variable ratio transformer for supplying a variable voltage to the circuit of the X-ray tube, said transformer having a single adjustable member for effecting a change in the transformation ratio, means for supplying different filament voltages to said X-ray tube to establish a plurality of different selected rates of current flow therein when energized, a plurality of scales having different calibrations corresponding to said diiferent rates of tube current, an index mark common to both said scales and movable relative thereto, means operable in coordinated relation with said movable member for effecting said relative movement of said plurality of scales and said index mark to indicate the final kilovoltage applied to said tube corresponding to the selected tube current, and means providing for making readable only the selected one of said scales having the proper calibration corresponding to the selected value of tube current.

5. In an X-ray control system having a variable ratio transformer for providing a variable voltage applicable to the circuit of the tube, said variable ratio transformer having an adjustable member, means for preselecting the filament voltage of the tube to predetermine the current through the tube when energized, switch means for applying a selected voltage of said transformer to the tube circuit, means under control of the operator for normally causing the closing of said switch means, means responsive to the settings of said adjustable member and said preselecting means for preventing the closing of said switch means by said operator controlled means when said transformer and said filament voltage are adjusted. to values which would be damaging to the tube, and means operable immediately upon movement of said adjustable member and said preselecting means to said damagingvalues and prior to actuation of said operator controlled means for affording the operator an indication of the operation of said preventing means.

6. In an X-ray control system having a variable ratio transformer for providing a variable voltage applicable to the circuit of the tube, said variable ratio transformer having an adjustable member, means for preselecting the filament voltage of the tube to predetermine the current through the tube when energized, switch means for applying a selected voltage of said transformer to the tube circuit, blocking means controlled by the settings of said adjustable member and of said preselecting means independently of the actuation of said switch means for preventing the closing of said switch means when said transformer and said filament voltage are adjusted to values which would be damaging to the tube, and means responsive to the operation of said blocking means for affording the operator an immediate indication prior to operation of said switch means of an adjustment of said transformer and of said filament voltage which would be damaging to said tube.

'7. In an X-ray control system having a variable ratio transformer for providing a variable voltage applicable to the circuit of the tube, said variable ratio transformer having an adjustable member, means for preselecting the filament voltage of the tube to predetermine the current through the tube when energized, switch means for applying a selected voltage of said transformer to the tube circuit, means under control of the operator for effecting the closing of said switch means to energize said tube, means for preventing the closing of said switch means when the setting of said transformer and the selected value of tube current are within a range which would be dangerous to the tube, and means operable directly upon the movement of either said adjustable member or said preselecting means into said specified range for indicating to the operator prior to the operation of said operator-controlled means that said setting of the transformer and said preselected value of tube current are within said specified range.

8. In an X-ray. control system the combination of a step-up transformer directly connected to the X-ray tube, a continuously variable-ratio transformer for supplying said step-up transformer with a Variable voltage and having a movable member for adjusting the ratio of transformation thereof, a reversible power motor for operating said movable member, selective operator-actuated controls for said motor providing for power adjustment of said movable member to select a predetermined voltage condition to be applied to said tube, and means operated by said movable member for preventing the closing of the circuit through said transformers when said movable member is adjusted to a voltage condition which would be damaging to said tube.

9. In an X-ray control system the combination of a step-up transformer directly connected to the X-ray tube, a variable ratio transformer for supplying said step-up transformer with a variable voltage and having a movable member for adjusting the ratio of transformation thereof, a reversible power motor for operating said move able member, selective operator-actuated controls for said motor providing for power adjustment of said movable member to select a predetermined voltage condition, and means for disabling further operation of said power motor at either limit of travel of said movable member.

10. In an X-ray control system the combination of a control panel, a voltage regulating transformer behind said panel for applying a predetermined operating voltage to the circuit of the X-ray tube, said transformer having a movable member behind said panel for changing the transformation ratio thereof, motive power means for operating said movable member 10- cated behind said control panel, push button control means accessible upon the face of said panel for controlling said power means to raise or lower the voltage of said transformer, means operatively coupled with said movable member and readable on the face of said panel providing an indication of the setting of said movable member and of the voltage of said transformer, and means on said panel for roviding an immediate indication of the raising of said voltage to a value which would be damaging to said tube.

11. In an X-ray control system the combination of a control panel, a voltage regulating transformer behind said panel for applying a predetermined operating votlage to the circuit of the X-ray tube, said transformer having adjustable means behind said panel for changing the voltage delivered thereby, motive power means for operating said adjustable means located behind said control panel, means accessible upon the face of said panel for controlling said power means to raise or lower the voltage of said transformer, said panel having a sight opening therethrough and a scale continuously calibrated in kilovolts movable with said adjustable means and positioned for direct reading through said opening in said panel.

12. In an X-ray control system the combination of a control panel, a voltage regulating transformer behind said panel for applying a predetermined operating voltage to the circuit of the X-ray tube, said transformer having a single adjustable member behind said panel for changing the voltage delivered thereby, motive power means for operating said adjustable member located behind said control panel, means accessible upon the face of said panel for controlling said power means to raise or lower the voltage of said transformer, means on said panel for indicating to the operator the setting of said transformer, means on said panel for preselecting the filament voltage to provide a predetermined tube current, a plurality of scales calibrated in different values corresponding to the effective peak values of transformer voltage at different values of tube current, an index mark common to both said scales and movable relative thereto, means operable in coordinated relation with said adjustable member for efiecting said relative movement of said plurality of scales and said index mark to indicate the final kilovoltage applied to the X-ray tube corresponding to the selected tube current, and means operating in coordinated relation with said filament voltage selecting means for making visible upon the front of said panel only the scale corresponding to the selected value of the tube current.

13. In an X-ray control system thecombination of a continuously variable transformer for supplying a variable voltage to the circuit of the X-ray tube, a control relay for completing the circuit from said transformer to said tube, means for heating the filament of the X-ray tube, and a continuously adjustable regulating transformer in addition to said variable transformer operable while said tube is energized for maintaining a predetermined desired voltage supply to said continuously variable transformer and adjustable under load while maintaining a continuous circuit to said variable ratio transformer, said regulating transformer providing for continuous adjustment of the voltage applied to said tube circuit during the time that said control relay has 16 completed the circuit thereto substantially free of line surges and abrupt changes in voltage.

14. In an X-ray control system the combination of a continuously variable transformer for supplying a variable voltage to the circuit of the X-ray tube, means for varying the ratio of said transformer in increments which are sufiiciently small to avoid damage to the X-ray tube while maintaining a continuous circuit, a control relay for completing the circuit from said transformer to said tube, means for selecting and establishing a predetermined filament current in said X-ray tube, a voltage regulating transformer separate from said continuously variable transformer for adjusting the voltage applied to said variable ratio transformer in a smooth and continuous manner substantially free of surges, said transformers and said filament current selective means being adjustable while said tube circuit is closed providing for selection of predetermined desired values of applied voltage and tube current.

DAVID SUSSIN. WILLIAM C. KUHLMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

